[flang-commits] [flang] [mlir] [RFC][mlir] Conditional support for fast-math attributes. (PR #125620)

[Mehdi Amini via flang-commits]

================
@@ -22,31 +22,60 @@ def ArithFastMathInterface : OpInterface<"ArithFastMathInterface"> {
 
   let cppNamespace = "::mlir::arith";
 
-  let methods = [
-    InterfaceMethod<
-      /*desc=*/        "Returns a FastMathFlagsAttr attribute for the operation",
-      /*returnType=*/  "FastMathFlagsAttr",
-      /*methodName=*/  "getFastMathFlagsAttr",
-      /*args=*/        (ins),
-      /*methodBody=*/  [{}],
-      /*defaultImpl=*/ [{
+  let methods =
+      [InterfaceMethod<
+           /*desc=*/"Returns a FastMathFlagsAttr attribute for the operation",
+           /*returnType=*/"FastMathFlagsAttr",
+           /*methodName=*/"getFastMathFlagsAttr",
+           /*args=*/(ins),
+           /*methodBody=*/[{}],
+           /*defaultImpl=*/[{
         ConcreteOp op = cast<ConcreteOp>(this->getOperation());
         return op.getFastmathAttr();
-      }]
-      >,
-    StaticInterfaceMethod<
-      /*desc=*/        [{Returns the name of the FastMathFlagsAttr attribute
+      }]>,
+       StaticInterfaceMethod<
+           /*desc=*/[{Returns the name of the FastMathFlagsAttr attribute
                          for the operation}],
-      /*returnType=*/  "StringRef",
-      /*methodName=*/  "getFastMathAttrName",
-      /*args=*/        (ins),
-      /*methodBody=*/  [{}],
-      /*defaultImpl=*/ [{
+           /*returnType=*/"StringRef",
+           /*methodName=*/"getFastMathAttrName",
+           /*args=*/(ins),
+           /*methodBody=*/[{}],
+           /*defaultImpl=*/[{
         return "fastmath";
-      }]
-      >
+      }]>,
+       InterfaceMethod<
+           /*desc=*/[{Returns true iff FastMathFlagsAttr attribute
+                         is applicable to the operation that supports
+                         ArithFastMathInterface. If it returns false,
+                         then the FastMathFlagsAttr of the operation
+                         must be nullptr or have 'none' value}],
+           /*returnType=*/"bool",
+           /*methodName=*/"isArithFastMathApplicable",
+           /*args=*/(ins),
+           /*methodBody=*/[{}],
+           /*defaultImpl=*/[{
+        return ::mlir::cast<::mlir::arith::ArithFastMathInterface>(this->getOperation()).isApplicableImpl();
+      }]>];
 
-  ];
+  let extraClassDeclaration = [{
+    /// Returns true iff the given type is a floating point type
+    /// or contains one.
+    static bool isCompatibleType(::mlir::Type);
+
+    /// Default implementation of isArithFastMathApplicable().
+    /// It returns true iff any of the results of the operations
+    /// has a type that is compatible with fast-math.
+    bool isApplicableImpl();
+  }];
+
+  let verify = [{
+    auto fmi = ::mlir::cast<::mlir::arith::ArithFastMathInterface>($_op);
+    auto attr = fmi.getFastMathFlagsAttr();
+    if (attr && attr.getValue() != ::mlir::arith::FastMathFlags::none &&
+        !fmi.isArithFastMathApplicable())
+      return $_op->emitOpError() << "FastMathFlagsAttr is not applicable";
----------------
joker-eph wrote:

```suggestion
      return $_op->emitOpError() << "has flag " << stringify(attr.getValue()) << " but fast-math flags are not applicable (`isArithFastMathApplicable()` returns false)";
```

https://github.com/llvm/llvm-project/pull/125620